4:00pm - 5:00pm|
Chemistry Physical Seminar: Dr. Stephen K. Doorn, “Photophysics and Quantum Emission Behavior of Carbon Nanotube Defect States”
Abstract: Red-shifted emitting states in carbon nanotubes, introduced by chemically stable and synthetically tunable covalently-bound dopants,1,2 are gaining attention for their potential to boost photoluminescence (PL) quantum yields,1,2 add new functionality,3,4 and serve as single photon emitters.5,6 These sites present a rich array of new photophysics, with dependences on specific functionalization chemistry and environmental interactions. As examples, low-T photoluminescence probes of defect-state electronic structure will be presented for sp3 defects introduced by aryl functionalization7 and compared to quantum chemical theory and results on oxygen-introduced defects.8 Exciton localization at defect sites9 and conversion to the new emitting states will be discussed in the context of the consequences localization has for relaxation dynamics and functionality. A significant increase (up to 10-fold) in exciton lifetimes results.10 Dependence of lifetimes on nanotube chirality and specific dopant suggest multiphonon relaxation mechanisms.10 Finally, defect-site localization paired with nanotube structural tunability will be shown as a route to room temperature single photon emission at telecom wavelengths.5,6 Control over chemical functionality and dielectric environment will be shown as routes for optimizing single photon emission behaviors. Results will be summarized with a brief perspective on possible future directions.
References: 1. Ghosh, S. et al., Science, 330, 1656 (2010). 2. Piao, Y. et al., Nature Chem., 5, 840 (2013). 3. Kwon, H. et al., J. Phys. Chem. C, 119, 3733 (2015). 4. Akizuki, N. et al., Nature Comm., 6, 8920 (2015). 5. Ma, X. et al., Nature Nanotech., 10, 671 (2015). 6. He, X. et al., Nature Photonics, 11, 577 (2017). 7. He, X. et al, ACS Nano, 11, 10785 (2017). 8. Ma, X. et al., ACS Nano, 8, 10782 (2014). 9. Hartmann, N. et al., Nanoscale, 7, 20521 (2015). 10. Hartmann, N. et al., ACS Nano, 10, 8355 (2016).
|Location: ||Hutchison Hall 473 (RC)|
Posted by: Evelyn Sucy-Caffery, Chemistry, 22-Dec-17 9:56am ET